A communication scheme that simultaneously performs transmission destined for multiple wireless communication terminals (hereinafter, terminals) or reception from the multiple terminals and is called OFDMA (Orthogonal Frequency Division Multiple Access) has been known. OFDMA that allocates one or more subcarriers as a resource block to a terminal and simultaneously performs transmission to multiple terminals or reception from the multiple terminals on a resource block basis is specifically called a resource-block-based OFDMA in some cases. Simultaneous transmission from a base station to multiple terminals correspond to downlink OFDMA transmission. Simultaneous transmission from the multiple terminals to the base station corresponds to uplink OFDMA transmission.
In a case where communication is executed through resource-block-based OFDMA in a wireless LAN system in conformity with IEEE 802.11 standard using CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance), presence of terminals that are not targets of OFDMA in the system is required to be considered. The terminals that are not OFDMA targets are terminals that do not serve as the targets of OFDMA executed in this case.
When OFDMA communication is performed in an environment where a terminal not serving as an OFDMA target (non-target terminal) resides, the non-target terminal does not successfully receive frames (more specifically, physical packets including frames) that are exchanged in OFDMA. Consequently, an error is detected in the physical layer or MAC layer. Accordingly, in the next access to a wireless medium, an EIFS (Extended Interframe Space) period is set as a fixed period of time to perform carrier sensing on the MAC layer. The EIFS period is longer than DIFS/AIFS [AC] which is a fixed period of time used in carrier sensing performed in normal medium access. Consequently, unfairness occurs between non-target terminals and the other terminals (e.g., terminals and a base station that execute OFDMA communication) in access right obtaining opportunities.